Nonhalation photographic element



Oct. 14, 1941 NONHALATION PHOTOGRAPHIC ELEMENT Filed Sept. 26, 1938 mprisinq an also/r al soluble 1-4 carbon aToms and a cellulose alkyl ether of anti-halation material.

INVENTOR.

ATTORN EY Patented Oct. 14, 1941 NONHALATION PHOTOGRAPHIC ELEMENT John R. Hill, Parlin, N. 1., assignor to Du Pont Film Manufacturing Corporation, New York, N. Y., a corporation of Delaware Application September 26, 1938, Serial No. 231,818

6 Claims.

Thisinvention relates to a light-sensitive photographic element having a removable backing; more particularly, it relates to a light sensitive photographic film having a removable light absorbing backing; stillmore particularly it relates to a light-sensitive photographic film having a water-insoluble removable backing containing a dye which is absorptive of light of all wave lengths to which the film is sensitive.

It is an object of this invention to provide a water-insoluble coating for light sensitive photographic elements which may readily be removed from the same by organic solvents. A further object is to provide a removable backing for a photographic film containing a solvent soluble dye in which the dye will not transfer to the base during storage. A still further object is to provide a removable dyed anti-halation coatin for photographic film elements which are free from tackiness and photographic active substances andhave a resistance to abrasive forces when dry. Still other objects will be apparent from a consideration of the hereinafter described invention.

The above and other objects are accomplished by the use of water-insoluble organic solventsoluble loweiyalkyl ethers of cellulose. In a more solution in a mixture of 80% toluene and ethanol by volume at C.) gives an excellent product for use according to this invention which has a maximum solubility in ethanol and other solvents. The ethyl ethers of cellulose having the above-described characteristics are preferred.

limited sense the invention comprises a photographic element having a sensitized emulsion upon one side of a transparent support and a coating of a cellulose lower alkyl ether of the type which is insoluble in water and is not injuriously softened thereby, but-which is soluble in water-soluble monohydric alcohols and wateralcohol mixtures and contains dye which is ab-' sorptive of light of all wave lengths to which said emulsion is sensitive. The dyes may vary widely in chemical structure and properties but should be soluble tothe extent of at least 1% in an organic solvent.

In the preferred embodiment of the invention, the removable backing coating is composed of methyl cellulose or ethyl cellulose which is insoluble in water and is not injuriously affected thereby, but is soluble in ethanol or a waterethanol mixture containing at least 50% and 7 preferably at least 70% of the latter, and a dye j having the above-described absorption chariacteristics.

The cellulose ethers in general should have an alkoxy content of at least 2.2 mols per Ce unit of the cellulose nucleus. In the .case of ethyl cellulose it has been found that an ethoxy content of 2.43 to 2.54 mols per Cs unit and a viscosity of 45 to 50 centipoises (determined on a 5% In investigating these ethers the surprising discovery was made that the addition of a dye to the cellulose ether before coating of the same upon the base had a very definite effect upon the adherence of the same to the film base. For instance, it was found that when ethyl cellulose was coated upon a cellulose acetate film base the dry layer could be stripped off even though the coating solution contained an active solvent for the base. Upon adding a dye to the coating it became more adherent. The adherence was found to be more pronounced if the ratio of the dye was controlled" within the narrow limits of 0.5 'to 0.9 part of dye to one part of cellulose ether. l 'v The invention will be further illustrated but is not intended to be limited by the following examples inwhich the parts stated are parts by weight unless otherwise indicated.

In the accompanying drawing a film support I. composed of a transparent cellulose derivative has coated on its'supper surface a light sensitive silver halide emulsion 2 and on its rear surface an anti-halation coating 3 composed of a waterinsoluble alcohol-soluble cellulose lower alkyl ether and an' anti-halation material.

Example I An alcohol soluble ethyl cellulose having a viscosity of 45 centipoises and an ethoxy content of 2.50 mols per Ca unit was incorporated in the following composition:

which was coated by means of a beading roller on the back side of a transparent cellulose acetate fllmbase which carried upon its face a panchromatic emulsion and allowed to dry. The coating was strongly adherent. The film was exposed in a camera, processed, and then placed into a bath containing ethanol and 30% water, whereupon the backing layer was dissolved off. Upon examination the film was found to be entirely free from the backing coating and un-- stained.

Similar results were obtained by substituting equivalent amounts of the following spirit soluble dyes; Naphthol Blue-Black (C. I. 246), Durol Black (C. I. 307), Sulfon Blue (C. I. 208),. VictoriaGreen (C. I. 657), Helvetia Green (C. I. 660), Brilliant Green (C. I. 662), Acid Green (C. I. 666), Wool Fast Blue (C. I. 833), Victoria Blue (0. I. 729), and Fast Black- (0. I. 919) in similar amounts.

A coating solution of the following composition:

Per cent Ethyl cellulose 1.5 Magenta (C. I. 677) 0.8 Ethanol 97.7

- was coated upon the back of a film which carried upon its face an orthochromatic emulsion and dried. The coating was strongly adherent and free from coating streaks and tackiness. After exposure and processing the film ,was incorporated into a water-ethanol bath containing about 75% of the latter, whereupon the dyed backing layer was readily removed. Upon inspection the base was found to be clean and entirely free from Example III A coating solution of the following composition:

Per cent Propyl cellulose 1.5 Durol Black (C. I. 307) 0.5 Ethanol 98.0

was coated upon the back of a film base which carried upon its face a panchromatic emulsion and dried. The coating was quite adherent, free from coating streaks and non-tacky. After exposure in a camera and processing the film was incorporated into a'water-alcohol bath containing about 80% of the latter, whereupon the antihalation layer was readily removed. After removal from the bath the base was found to be clean and entirely free from stain and coating particles. The propyl cellulose in this example contained a propoxy content of 2.48 mols per 06 unit and was water insoluble.

In place of the specific ethers of the above examples any ether having the characteristics hereinbefore mentioned may be substituted. Thus, the cellulose isopropyl, butyl and isobutyl ethers which are alcohol or alcohol-water soluble. but water-insoluble may be substituted in like amount.

While it has been stated that the cellulose ether dyed layer is not soluble or removable in water alone, it is to be understood that this is to mean that it is so little afl'ected during the period of time which it.is in contact in aqueous .solutions during the usual photographic processes. that no visible change is apparent.

. The ethers of this invention are not only soluble in 'water-alcohol mixtures and water soluble alcohols, but are soluble in organic solvents in gen]- alcohol removal solutions. Other organic solvents may be mixed with the alcohols or wateralcohol mixtures or the former may be used alone. It is to be understood, however, that the wateralcohol mixtures are the preferred removal solvents. As examples of other solvents mention is made of ethyl ether; chlorinated hydrocarbons.

e. g. chloroform, carbon tetrachloride, trichloroethylene; acetone, methyl alcohol, benzene, toluene, xylene, nitrobenzene, etc. and mixtures thereof. The solvents used, however, should not affect the film base. As examples of other useful water-soluble alcohols, mention is made of methanol, isopropanol, n-propanol and n-butanol. These may be used in admixture with the above solvents. y

In general, any dye which possesses the property of absorbing actinic light, of being readily dissolved or destroyed in ordinary photographic baths and of not such baths may be used. The dye or dyes to be used in any specific instance are primarily determined by the light sensitivity of the emulsion. Such emulsions are .usually gelatin silver halide emulsions which contain sensitizers such as cyanine, carbocyanine, psuedo-cyam'ne, cyazine bases and salts. That is, it must be absorptive of light of the wave lengths to which the emulsion is sensitive. In general the dye should be added in an amount sufiicient to give a photographic density of 0.8 or the amount of dyed layer should be sufficient to give such a density. As examples of additional useful dyes, mention is made of: I

Auramine (C. I. 655) Chrysoin (C. I. 148) eral. Thus, it is not necessary to use only water- Acid Blue Black (C. I. 246) Rhodamine (C. I. 749, 750, 751, 746, 753, 761, 763) Fuchsin (C. I. 677) Safranine G (C. I. 841) Ponseau GR (186) Crocein Scarlet (C. I. 277, 251, 286, 252, 291, 183) Azorubin (C. I. 179) Safranine O (C. I. 841) Ponseau 2R (C. I. 79)

Spirit Solution Nigrosine (C. I. 864) Metanil Yellow (C. I. 138) This invention possesses the advantage that a nontacky anti-halation layer which is readily soluble in alcohol and water alcohol mixtures may be quickly prepared. A further advantage resides in the fact that a non-halation layer which is strongly adherent to film base may be economically prepared. A still further advantage is that a film which is not stained by a dyed antihalation layer is provided. Other advantages will be apparent to those skilled in the art.

As many apparently widely different embodiments of this invention may be made without departing from the spirit and scope thereof, it is to be understood that I do not limit myself to Iclaim 1 1. A photographic film element comprlsing a light-transmitting support, a light sensitive emulsion layer on one face thereof and a layer consisting of a water-insoluble ethyl cellulose which is soluble in water-ethanol mixtures predominating inthe latter, said layer containing from 0.5 to 0.9% of a dye which is absorptive of light of all wave lengths to which said emulsion is sensitive carried upon the opposite face.

2. A photographic element comprising a light transmitting support, a light sensitiveemulsion layer on one face thereof and a layer consisting of a water-insoluble ethyl cellulose which is soluble in ethanol-water mixtures containing at least 70% of the former, said layer containing from 0.5 to 0.9% of a dye which is absorptive of all wave lengths to which said emulsion is sensitive carried upon the opposite face.

3. A photographic element comprising a light transmitting support, a light sensltiveemulsion layer on one face thereof and a layer consisting of a cellulose ethyl ether having an ethoxy content of 2.43 to 2.54 mols per 06 unit, said layer containing from 0.5 to 0.9% of a material which absorbs actinic light carried upon the opposite face.

4. A photographic element comprising a light transmitting support, a light sensitive silver halide emulsion layer on one face thereof and a layer consisting of a cellulose ethyl ether having an ethoxy content of 2.43 to 2.54 mols per Ce unit, said layer containing from 0.5 to 0.9% of a dye 6. A photographic film element comprising a light transmitting support, alight sensitive silver halide emulsion layer on one face thereof and a layer consisting of a water-insoluble cellulose lower alkyl ether which is soluble in waterethanol mixtures predominating in the latter, said layer containing from 0.5 to 0.9% of a dye which is absorptive of light of wave lengths to which said emulsion is sensitive.

JOHN R, HILL. 

